1. Field of the Invention
The present invention is directed to a single-pole relay switch, and more particularly to a relay switch with a pair of fixed contact which are conducted with or interrupted from each other by a common movable member in an arc-extinguishing environment.
2. Description of the Prior Art
U.S. Pat. No. 5,892,194 discloses a contact device with a pair of fixed contacts which are closed and opened by a common movable contact within a sealed compartment of an elongated configuration. The fixed contacts are spaced along the length of the compartment and form a pair of two parallel opening paths or gaps with the movable contact moving away from the fixed contacts. Permanent magnets are disposed around the compartment to generate a magnetic field which drives arcs each extending between the movable contact and the fixed contacts for stretching arcs in opposite directions of moving the individual arcs away from each other towards the opposite end walls of the compartment for rapid extinction of the arcs. However, this arc drive is effective only when the current flows in one predetermined direction. That is, when fixed contacts are connected oppositely to flow the current in the direction opposite the predetermined direction, the individual arcs are driven by the magnetic field to stretch towards to each other, resulting in merger of the arcs which causes undesired shorting between the fixed contacts through the merged arc. Thus, the above prior contact device requires to be connected only in a predetermined current direction for making the use of the arc drive by the permanent magnets.